2.1.2 [Ionic bonding] Flashcards
What is ionic bonding?
Strong electrostatic forces of attraction between oppositely charged ions.
What are the features of ionic bonding?
Ionic bonding occurs between a metal and a non metal. Electrons are transferred from the metal to the non-metal to form full outer shells.
Transfer of electrons creates ions. Oppositely charged ions attract through electrostatic forces to form a giant lattice.
What is the strength of an ionic bond dependant on?
The charge of an ion is related to the strength of the ionic bond that forms. Ions with greater charge have greater attraction to the other ions resulting in stronger forces of attraction and therefore stronger ionic bonds.
Larger ions have a greater atomic radius have weaker attraction to the oppositely charged ions because the attractive forces have to act over a greater distance. For same charge smaller ions have higher electrostatic forces of attraction due to less shielding also due to them being more tightly packed in a lattice
How do Ionic compounds conduct electricity?
Solid ionic compounds do not in general conduct electricity because there are no delocalised electrons ions are not free to move.
However molten ionic compounds will conduct since the ions migrate towards the electrodes of opposite sign of potential difference is applied.
Aqueous solutions of ionic compounds also conduct electricity and undergo electrolysis.
What are the physical properties of ionic compounds?
High melting points
Brittleness
Poor electrical conductivity when in solid but good when molten
Often soluble in water
Why do ionic compounds have high melting temperatures?
Ionic solids consist of a giant lattice network of oppositely charged ions. There are many ions in the lattice and the combined electrostatic forces of attraction among all of the ions is large so large energy is required to overcome attraction to break ions free from lattice.
Why are ionic compounds brittle?
if stress is applied to a crystal of an ionic solid then the layers of ions may slide over one another.
Why are ionic compounds soluble?
Many ionic compounds are soluble in water. Energy required to break lattice structure and separate ions. Both positive and negative ions are attracted to water molecules because of the polarity which water molecules posses.
What is the evidence for the existence of ions?
Ability of ionic compounds to conduct electricity and undergo electrolysis when either molten or aqueous solution. When a direct current is passed through molten sodium chloride. Sodium is formed at the negative electrode and chlorine is formed at the positive electrode.
+ ion migrates towards negative electrode when gain electron
- ion migrate towards positive electrode when lose electron
What does isoelectronic mean?
Isoelectronic means all atoms have same number of electrons so same electron configuration
Show a dot and cross diagram for an ionic compound?
